The present invention relates to sample tracking systems and, more particularly, to a sample tracking system to provide for writing sample data on a sample container.
A major objective of the present invention is to provide for flexible and reliable sample tracking for forensic chemical analysis labs. In forensic analysis it is necessary that the sample to which a description refers be identifiable, even years after analysis is completed.
A prevalent concern of such laboratories is the considerable amount of paperwork required to track a sample through various stages of collection, distribution, preparation and chemical analysis. It is commonly understood that in a given study, there is about a 60% to 70% chance of clerical error, and a significant proportion of these result in misidentification of a sample. In court, this could translate into strong evidence against the wrong suspect. More generally, this error rate largely undermines the validity and, thus, usefulness of chemical analysis in establishing the guilt of a polluter or drug user "beyond a reasonable doubt".
In a typical laboratory procedure there are plenty of opportunities for error. Collection can involve, for example, filling a bottle with river water downstream of a suspected polluter. Inevitably, this bottle will be stored among many similar bottles. It is therefore important that the bottle be uniquely identified so that information such as the time, date and place of collection be determinable at all times in the ensuring analytical and forensic chain of events. Ideally, the time, date and place are indicated on the sample bottle. The data may be handwritten on a label, either before or after application to the container. Opportunity for error exists in application of a label prepared off the bottle or, at a later stage, reading the handwriting in the bottle. A portable printer can be used to overcome legibility problems, but then there is a greater chance of a typographical or other input error.
Once the sample is brought into the laboratory, it is usually transferred to several bottles. The information must be transferred to the new bottles as well as to the laboratory data base, providing further opportunities for reading and data entry errors. Similar errors can occur at sample preparation and analysis. Various levels of redundancy can be built into a procedure, but usually add complexity, and thus additional opportunities for error.
The opportunity for mistakes in data entry and reading can be largely eliminated by using bottles with pre-printed serialized bar code labels at each step of the laboratory procedure. However, preprinted bar code labels do not lend themselves to time, date and location data, thus not meeting legal requirements for some studies. Furthermore, while pre-printed labels can include text as well as bar code, it is difficult to conceive of a system for providing mnemonically encoded data on a pre-printed label. The lack of mnemonic codes increases the chances of human error during manual analytic, inventory and forensic procedures.
What is needed is a sample tracking system providing for flexible and reliable sample tracking. Such a system should minimize opportunities for read and write errors, both in the field and in the laboratory. In addition, the system should permit considerable flexibility in assigning mnemonically encoded data to be displayed on a container label. Further, the system should be simple to use, without requiring redundant operator procedures.